Ribbon-feed mechanism



June 18, 1929. J. H BARR.

RIBBON FEED uscnAnIsu Filed May 9, 1927 3 Sheets-Sheet ATTORNEY Ssl.5une18,1929. 1.717.362

mason FEED umcnamsu Filed May 9, 1927 5 Sheets-Sheet 2 hi1: Ii Ill 5INVENTOR (75km li Barr ATTORNEY Jun 1929- J. H. BARR 1.711.362

RIBBON FEED uzcnlmlsu Filed May 9, 1927 3 Sheets-Sheet 3 INVENTOR $7M, HBelfr- ATTORNEY Patented June 18, 1929.

PATENT OFF'ICEL.

JOHN H. BARR, OF n'naoa, NEW YORK.

RIBBON-FEED MECHANISM.

Application filed May 9,

This invention relates to ribbon feed mechanisms for typewriters andsimilar printing devices, and has for its objects the production-of asimple and positive mechanism by which the ribbon is fed at eachprinting stroke, together with a quick acting automatic ribbon reversemechanism operating on a single stroke of a key, and simple means forrewinding and changing ribbons. Other objects are to avoid unnecessaryfriction and binding, to prevent accidental displacement of themechanism by vibration or driving forces, to make a construction whichis read ily adapted to quantity production under modern manufacturingprocesses and in general to produce an eflicient and convenient deviceof the class described. Various other objects will become apparent asthe description proceeds.

In the drawings forming part of this specification, 1

Fig. 1 is a plan view of the ribbon shift mechanism in one position ofoperation.

Fig. 2 is a similar plan View showing the feed shifted to the reverseposition of opera tion.

Fig. 3 is a detail of the spool device and return release.

Fig. 4 is a view in elevation of the ribbon feed showing the ribbonshift mechanism,

and one ribbon spool assembly. 7 1

Fig. 5 is a detail in elevation of the yieldable detent bearing for thecross-shaft.

Fig. 6 is a detail view partly in cross-section on theline AA-of Fig. 5.

Fig. 7 is a detail plan view of aworm feed and cross-shaft bearing.

Fig. 8 is a plan view of the ribbon feed ratchet. i v Fig. 9 is anelevation of the same in one position of operation.

F 10 is a similar elevation in a second position of operation.

Similar reference numerals refer to the same parts thruout the variousviews.

Referring first to Fig. 1 and Fig. 2, the typewriter ribbon 1 is mountedto travel between two spools 2 and 2, on which it winds and unwinds asis usual in typewriters. Inasmuch as the present invention concernsimprovements in the means for driving these spools :3 and Q, and forreversing the direction of travel when the end of the ribbon has 1927.Serial No. 189,890.

been reached, I will first describe the mech-, anism by which the spoolsare rotated, and then describe the means by which the direction ofrotation of the spools is reversed when desired.

Referring now more especially to Fig. 4, the spool 2 is detachablymounted on the upper end of the shaft 3, so as to rotate therewith-theshaft 3 beingjournalled for rotation in the ears 4 and 5 of thesupporting bracket 6. In order that the spool 2 and shaft 3 may not runtoo easily and overtravel, a compression spring 7 is mounted on theshaft 3 between the collar 8 and the bearing car 4-this spring 7creating enough frictional drag on the shaft 3to keep the spools fromunwinding too freely. The shaft 3 is driven thru a pair of cams orratchets 3' which are carried on a hub secured to the lower end of theshaft 3, as shown for example in Fig. 3 and Fig. 4C. These cams 3 havean inclined face and a perpendicular face, and whenthe shaft 3 is beingdriven the perpendicular face is engaged by one of the spokes of theworm wheel 9, forming a positive drive. As shown for example in Fig. 3,it is desirable that the number of spokes of .the worm wheel 9 shoulddiffer from the number of cams o-r tceth ,3, so as to reduce the angulartravel necessary for engagement. Variouscombinations of numbers ofspokes and numbers of teeth may of course be used. The worm wheel 9 isloosely mounted on the shaft 3, and'free to slide vertically thereonuntil its hub strikes the lower side of the ear 5the clearance beingsufficient to permit the spokes of the worm whel 9 to ride up over thetops of the inclined faces of the cams 8 if the spool shaft 3 is turnedin the proper direction. This permits a rapid winding by turningtlio'spool 2 by hand, when changing a ribbon, as will be described. Thespring 7 serves to hold the shaft 3 down in place, so that there isalways sufficient clearance for the worm wheel 9 to ride up. The wormwheel 9 is'rotated by a worm 10, which. is mounted on a worm shaft 11,as clearly shown in Fig. 1 and Fig. 7. The worm shaft 11 extends acrossto ope ate the other spool 2 in a somewhat similar manner when thedirection of ribbon feed is reversed, as will be described (see Fig. 2).

The cross shaft 11, at. about its middle point, (see Fig. 1) has aratchet wheel 12 secured thereto, which is operated by a pawl 13 shownin Fig. 4, and also more in detail in Fig. 8, Fig. 9, and Fig. 10. Theratchet wheel 12 is substantially in the middleof the shaft 11, so as tobe adjacent the pivot 32, in order that oscillations of the shaft 11about the pivot 32 will not seriously affect the relation of the ratchet12 to the pawl 13the ratchet merely shifting slightly sideways along theedge of the pawl tooth. The pawl 13 is yieldably attached to the link 14by means of the pin 15 and spring 16, which holds the pawl 13 in contactwith the ratchet 12, yet'permits the awl 13 to ride up on the returnstroke, as

hown for example in Fig. 10. The link 14 is pivotally connected by thepin 17 to the ears 18 which are secured to and form art of the bail 19.This bail 19 extends su stantially across the machine and is pivoted atits ends in the bearings 20, about which it may swing when struck by adriving member, such as 21. Each of the printing keys of the typewriteris provided with a driving member 21 which is actuated whenever aprinting key is pressed, so that whenever one of the keys is operatedsome one of the driving members 21 moves forward and strikes the bail19. Any

' suitable key actuated drivin element may be used, for example as shownin my copending application, Serial No. 26,850, filed April 30, 1925,for typewriter, and as the particular form of the key action does notconcern the present invention, it need not be described in furtherdetail here.

The swinging bail 19 has attached thereto a tension spring 22, whichserves to retract it after it has received the impulse of the drivingmember 21. The operation is clearly shown in Fig. 4, Fig. 9 and Fig. 10.Starting from the position shown in Fig. 9, the key actuated drivingelement 21 moves forward, strikes the bail 19, and swings it about thepivot 20 down to the position shown in Fig. 10. The pawl 13 engagin theratchet 12 1'0- tates it in the direction 0 the arrow. Since the pivots17 and 20 are approximately in the line of action at the start, asubstantially harmonic motion results, that is, the initial linearmotion of the pawl 13 is slow relative to the initial angular motion ofthe bail 19, but increases in speed as the motion progresses thusdriving the ratchet 12 Without unneces sary shock. On the return motion,as the driving element 21 recedes, the sprin 22 retracts the bail 19,and the pawl 13 rides up and back over the teeth of the ratchet 12. Arod 24 may extend to the ribbon vibrator, if desired, so that it mayalso be operated by the bail 19. p

The rotation of the ratchet 12 as described is transmitted thru'theshaft 11 to the worm 10 andworm wheel 9, which rotates the shaft 3andspool 2 to feed the ribbon 1 along step by step as the keys of thetypewriter are operated. It will be noted that by the constructiondescribed the ribbon is positively fed with each printing stroke but theribbon is not moved when operating the space bar or in the traverse ofthe carriage 'by-hand. This permits the ribbon to be used-in a uniformand economical manner.

:I will now, describe the mechanism by which the direct-ion'of travel ofthe ribbon is automatically reversed, so that it may be alternatelywound from one spool to the other, as long as desired, withoutattentionon the part of the operator.

' Referring more particularly to Fig. 1 and Fig. 2, in which the bail 19is only shown diagrammatically, and the ratchet driving pawl describedis omitted for the sake of clearness, the frame 30 which supports thebearings 31, 31' of the cross-shaft 11, is mounted on a fixed pivot at32 so that it may swing to a certain extent-permitting either one worm10 or the other worm 10 to be brought into contact with their respectiveworm wheels 9 or 9. To induce this swing of the frame 30 at the propertime, a second'frame 33 is mounted so that it may slide on the frame 30,and shift thereon longitudinallyof the cross-shaft 11. This frame 33 hasbearing ears 34 and 34 attached thereto, thru which pass the shaft 11-the shaft 11 being free to slide longitudinally therein as well asrotate.

Since the shaft 11 also passes thru the bearings 31, 31 of the frame 30,the frames 30 and 33 are thus connected together, with the frame 33being slidable on the frame 30 in the direction of the shaft 11.

Two clips 35, 35, having hooks 36, 36 are slidably mounted on thecross-bar of the frame 33, being held against the stops 37, 37 by thevsprings 38 and 38 respectively. At two points the bail-19 is providedwith projections 40 and 40, whieh'are spaced apart somewhat differentlyfrom the books 36. .36' so that the projections 40 or 40 can only engageone book 36 or 36 at a time.

After the frame 33 has been shifted into the proper position, the hook36 comes directly under the projection 40, and when the bail 19 is swungdownward as has been described, the

projection 40 strikes the hook'36 and swings the frames 30 and-33 aroundthe pivot 32 so as to withdraw the worm- 10 from engagementwith the wormwheel 9, that is, moving it from the position shown in Fig. 1 to thatshown in Fig. 2. At the same timethe worm 10 is swung into engagementwith the worm wheel 9'. Since the worms 10 and 10 have threads ofopposite pitch, this serves to reverse the motion of the ribbon spools 2and 2. The line of pull of the worm shaft. being somewhat ofiset fromthepivot 32, helps to hold the worm in engagement.

It may sometimes happen that when one of the hooks 36, 36 is in theprocess of being shifted under one of the projections 40, 40 it maypress against-the side ofthe projection I 19 from being. retracted bythe spring 22. It

is to obviate this possibility that the hooks 36, 36' are mounted onslidable-clips retained by yielding springs 38 and 38, instead of beingrigidly secured to the cross bar of the frame 33. If by chance one ofthe hooks 36, 36 bears against the side of the projection on the bail 19and threatens to stop it, the amount of force the hook can bring to bearis limited by the spring 38 or 38, and this is proportioned so as to beinsufficient to hold the bail 19 from returning.

Since only one impulse applied to the bail 19 is required to swing theframe 30 on the pivot 32, this shift operates on a single stroke of thetypewriter key, after the frame 33 has been moved into the properposition relative to the projections on the bail 19. In order to shiftthe frame 33 into the proper position, a air of forked levers 42 and 42-are provi ed,engaging pins 43 and 43on the frame 33. These levers 42 and42' are pivoted at 44 and 44' respectively, and the other ends of thelevers extend up into the path of the ribbon 1,

and are provided with slots 45 and 45 re spectively thru which theribbon passes. The ribbon 1 is provided with the usual clips 46 and46near each end, and when the ribbon is substantially unwound from aspool, such as 2 in Fig. 1, the clip 46, being too large to pass thruthe slot 45, carries the lever 42 along with the motionof the ribbon,and shifts the frame 33 in the direction of the spool 2. This brings thehook 36 under the projection so that when the bail 19 is swung down bythe next stroke of a typewriter key, the worm 10' is swung out of meshand the worm 10 is thrown into mesh, as shown in Fig. 1. Figs. 1 and 2show the positionafter the automatic shift has been effected. The spool2 then starts to wind up' the ribbon again. When the other end of theribbon is-reached, the clip 46 operates the lever 42 in a similarmanner, and shifts the worm 10' into driving engagement as shown in Fig.2, thus reversing thetravel of the ribbon.

The levers 42 and 42' have extensions 47 and 47 respectively attachedthereto, and connected by a light tension spring 48, which serves toreturn the frame 33 to its neutral or disengaged position, as soon asthe shift has been accomplished and the ribbon begins to wind up,relievin the pressure of the ribbon clips 46 or 46 against the slot or45. This keeps the hooks 36 and 36 normally out of line with theprojections 40 and 40', so that they will not continually be struck bythe swing of the bail 19.

In order to hold the shaft 11 in position after it has been shifted asdescribed, it passes at its ends thru bearings 50 and 50', which are ofthe yieldable detent type, as shown more particularly in Fig. 4, Fig. 5,Fig.- 6, and Fig. 7, as well as Fig. 1 and Fig. 2. This bearing cient tohold the shaft 11 from displacement.

spools by hand, may

50 is made of two parts 51 and 52-as shown in Fig. 5, held together bythe spring 53. The bearing parts 51 and 52 are relatlvely thin, so as topermit the shaft 11 to run in either of two non-parallel positionswithout binding. The part 51 is fixed to the supporting bracket 6, whilethe part 52 is pivoted at 54, and is provided with two recesses 55 and.56, with a tongue or detent projection 57 sep-' arating them. When theshaft 11 is in one position it fits in the recess 56, and when the shaft11 isshifted to the other position, as described, it fits in the recess55. When it shifts from one position to the other, the pressure of theshaft 11 on the tongue 57'raises the bearing cap 52 against the force ofthe spring 53 and permits the shift. After the shift has been made,'theton'gue 57 under the tension of the spring 53 is in general sufii- Inchanging ribbons it is desirable that both spools be permitted to turnfreel so that the operator, by spinning one o the the ribbon all on onespool. One mechanism for permitting this free winding has beendescribed, namely, the spokes of the wheels 9 or 9 being arranged tofreely over-ride on the inclined faces of the cams 3. This al lows thespool whose worm wheel is locked 9 by the-worm to be wound up freely byhand (though it cannot be turned by hand in the opposite direction),while the other spool, whose worm wheel is not engaged with its worm, isof coursefree to spin in either di rection, and so. can .unwind itsribbon on to the winding spool. r 3

My construction also permits another method whereby both spools arereleased for free winding, if desired. The cross-shaft 11 projectsslightly from each side of the machine, so that it can be reached by theoperators finger, and if this shaft 11 is moved by hand to a positionmidway between its two normal positions, both of the worms 1'0 and 10will be out of contact with their respective worm wheels 9 and 9, sothat both worm wheels will be free to spin. When the shaft 11 is in thismid-position, it will be under the detent tooth 57 of Fig. 4 and Fig. 5.While the detent will have a tendency to move the shift into one or theother of its normal positions, the shaft is easily held by the hand.This construction also permits a hand reverse when desired, as theoperator by the touch of a finger can throw the shaft 11 into the otherdetent notch and so reverse the ribbon.

In the foregoing I have explained and described a preferred form of myinvention in certain specific examples, but it will be understood thatthese-are only by way of illustration, and that the apparatus issusceptible of various modifications and; adaptations'as will beapparent to those skilled in the art,

able to rapidly wind any one of said members, a ratchet wheel,

and a pawl pivoted to said bail and adapted to drive the ratchet wheel,the pivot of the pawl and the pivotal axis of the bail beingsubstantially in the line of action of the pawl at the beginning of adriving stroke, whereby the starting shock is reduced.

2. In a ribbon feed mechanism, the combination of a cross-shaft mountedfor rotation on its own axis and for oscillation about a transverse axisintermediate its ends, spool driving gears on opposite sides of the axisof oscillation, corresponding gears on the cross-shaft arranged to drivethe spool gears in opposite directions and adapted to be broughtalternately into driving engagement by oscillation of the cross-shaft, asupporting bearing for said shaft having two sockets and a yieldabledetent projection between them, said bearing being proportioned so thatsaid shaft may shift from one socket to a nonparallel positionin theother socket.

3. In a ribbon feed mechanism the combination of a s 001 shaft, a gearloosely mounted on said sha t for both rotary and axial motion, and atooth mounted on said shaft and adapted to engage the gear, said toothhaving a driving face and an overrunning face, whereby in one directionof rotation the gear will drive theshaft, and in theother direction ofrotation the gear will over-ride the tooth and permit the shaft to turnfreely.

4. In a ribbon feed mechanism, the combination of a spool shaft, a wormwheel loosely mounted on said shaft for both rotary and axial motion, aworm adapted to mesh with said worm wheel, and a tooth mounted on saidshaft and adapted to engage the gear, said tooth having a driving faceand an over-running face, whereby ino'ne direction of rotation the gearwill drive the shaft, and in the other direction of rotation the gearwill over-ridethe tooth and-permitthe shaft to turn freely. w

5. In aribbon feed mechanism, the combination of a spool shaft, a gearloosely'mounted on said shaft for both rotary and axial mo tion, saidgear. having a plurality of spokes,

and a plurality of teeth mounted on said shaft and adapted to engage thespokes, the number of spokes differing from the number of teeth so as toreduce the angular travel necessary for engagement, said teeth havingdriving faces and over-running faces, whereby in one direction ofrotation the gear will drive the shaft, and in the other direction ofrotation the ear will over-ride the teeth andpermit the s aft to turnfreely.

6. In a ribbon feed mechanism, the combination of a spool shaft, a. wormwheel loosely mounted on said shaft for both rotary and axial motion,said gear having a plurality of spokes, a worm adapted to mesh with saidWorm wheel, and a plurality of teeth mounted on said shaft and adaptedto engage thespokes the number of spokes differing from the number ofteeth so as to reduce the angular travel necessary for engagement, saidteeth having driving faces and over-running faces, whereby in onedirection of rotation the gear willdrive the shaft, and in the otherdirection of rotation the gear will over-ride.

7 said movable member and said frame whereby the frame may be shifted onthe single oscillation of the movable member, means for bringing saidcooperating means into operative position, and means for withdrawing thecooperating means from operative position after reversal of the ribbon.

8. In a ribbon feed mechanism, the combination of a reversing framemounted to swing about a pivot, a cross-shaft journalled in said frame,a shifting frame having bearings for said shaft relative to which thecross-shaft may both rotate for driving and move longitudinally forshifting, means for moving said shifting frame longitudinally on thecross-shaft, and actuating mean adapted to engage the shifting frame ateither one of two points, whereby the shifting frame, shaft, andreversing frame may be swung about thepivot, and a ribbon feed mechanismarranged to be reversed thereby.

9. In a ribbon'feed mechanism, the combination of a reversing'framemounted to swing about a pivot, a cross-shaft journalled in said frame,a shifting frame having bearings for said shaftrelative to which thecrossshaft may both rotate for driving and move longitudinally forshifting, means for movingsaid shifting frame longitudinally on thecross-shaft, a pairofengaging means on said shifting frame capable ofyielding in the line of shifting, actuating means adapted to on gage oneor the other of said engaging means and move them transversely to theline of shifting, whereby the shifting frame, shaft, and reversing framemay be swung about the pivot, and a ribbon feed mechanism arranged to bereversed thereby.

10. In a ribbon feed mechanism, the combination of a reversing framemounted to swing about a pivot, a cross-shaft journalled in said frame,a shifting frame having bearin s for said shaft relative to which thecross-s aft may both rotate for driving and move longitudinally forshifting, means for moving said shifting frame longitudinally on thecross-shaft, means for restoring the shifting frame to a neutralposition, and actuating means adapted to engage the shifting frame ateither one of two points, whereby the shifting frame, shaft, andreversing frame may be swung about the pivot, and a ribbon feedmechanism arranged to be reversed thereby.

. 11. In a ribbon feed mechanism, the combination of a reversingframemounted to swing about a pivot, a cross-shaft journalled in saidframe, a shifting frame having bearings for said shaft relative to whichthe cross-shaft may both rotate for driving and move longitudinally forshifting, means for moving said shifting frame longitudinally on thecross-shaft, means for restoring the shifting frame to a neutralposition, a pair of engaging means on said shifting frame capable ofyielding in the line of shifting, actuating means adapted to engage oneor the other of said engaging means and move them transversely to theline of shifting, whereby the shifting frame, shaft, and reversing framemay be swung about the pivot, and a ribbon feed mechanism arranged to bereversed thereby.

12. In a ribbon feed mechanism, the combi'nationof a pair of ribbonspools, a ribbon arranged to wind and unwind between them, clips nearthe ends of the ribbon, slotted levers'adapted to be moved by saidclips, a shifting frame movable by said levers, bear-v ings carried bysaid shifting frame, a shaft mounted in said bearings for both rotaryand axial relative motion, a second frame pivoted intermediate. the twospools, bearings for said shaft on said second frame, whereby theshifting frame, second frame, and shaft are interconnected foroscillatory motion about the pivot of the second frame, over-runningclutch devices connected to drive said spools in opposite-directionsalternatively, gear wheels adapted to rotate the clutch devices, twodriving gears mounted on said shaft and'adapted to drive the gear wheelsalternatively in opposite directions, a ratchet wheel mounted on saidshaft intermediate the two driving gears, a 'ratchet drive mechanism forsaid ratchet, a pair of spaced engaging points on said shifting frame, apair of differently spaced engaging elements having an oscillatorymotion, whereby one or the other of said points on said shifting framemay be engaged when the frame is shifted, and the shaft swung about thepivot to engage one driving gear and disengage the other.

13. In a ribbon feed mechanism, the combination of a pair of ribbonspools, a ribbon arranged to wind and unwind between them, clips nearthe ends of the ribbon, slotted levers adapted to be moved by saidclips, a shifting frame movable by said levers, bearings carried by saidshifting frame, a shaft mounted in said beari'ngs for both rotary andaxial relative motion, a second frame pivoted intermediate the twospools, bearings for said shaft on said second frame, whereby theshifting'frame, second frame, and shaft are interconnected foroscillatory motion about the pivot ofthe second frame, means to steadysaid shaft in one or the other of its shifted positions, over-runningclutch devices connected to drive said spools in opposite directionsalternatively, gear wheels adapted to rotate the clutch devices, twodriving gears mounted on said shaft and adapted to drive the gear wheelsalternatively in opposite directions, a ratchet wheel mounted on saidshaft intermediate the two driving gears, a ratchet "drive mechanism forsaid ratchet, a pair of spaced engaging points on said shifting frame, apair of differently spaced engaging elements having an oscillatorymotion, whereby one or the other of said points on said shifting framemay be engaged when the frame is shifted, and the shaft swung about thepivot to engage one driving gear and disengage the other.

14. In a ribbon feed mechanism, the combi-" nation of a pair of ribbonspools, a ribbon arranged to wind and unwind between them, clips nearthe ends of the ribbon, slotted levers adapted to be moved by saidclips, a shifting frame movable by said levers, means for restoring saidshifting frame to a neutral position, bearings carried by said shiftingframe, a shaft mounted in said bearings for both rotary and axialrelative motion, a second frame pivoted intermediate the two spools,bearings for said shaft on said second frame, whereby the shiftingframe, second frame, and shaft are interconnected for oscillatory motionabout the pivot of the second frame, over-running clutch devicesconnected to drive said spools in opposite directions at ternatively,gear Wheels adapted to rotate the clutch devices, two driving gearsmounted on said shaft and adapted to drive the gear wheels alternativelyin opposite directions, a

ratchet wheel mounted on said shaft intermediatethe two driving ears, aratchet drive mechanism for said ratchet, a pair of spaced engagingpoints on said shifting frame, a pair ofdiiferently spaced engagingelements having an oscillatory motion, whereb one or the adapted to bemoved by said cli s, a shifting frame movable by said levers, earingscarried by said shifting frame, a shaft mounted in said bearings forboth rotary and axial relative motion, a second frame pivotedintermediate the two spools, bearings for said shaft on said secondframe, whereby the shiftingframe, second frame, and shaft areinterconnected for oscillatory motion about the pivot of the secondframe, over-running clutch devices connected to drive said spools inopposite directions alternatively, gear wheels adapted to rotate theclutch devices, two driving gears mounted on said shaft and adapted todrive the gear wheels alternatively in opposite directions, a ratchetwheel mounted on said shaft intermediate the two driving gears, aratchet drive mechanism for said ratchet, a pair of spaced engagingpoints on said shifting frame, a pair of differently spaced engagingelements having an oscillatory motion, whereby one or the other of saidpoints on said shifting frame may be engaged when the frame is shifted,and the shaft L swung about the pivot to engage one driving gear anddisengage the other, and yieldable means to limit the friction of saidengaging points and engaging elements when the shifting frame is beingmoved into operative'engagement.

16. In a ribbon feed mechanism, the combination of a pair of ribbonspools, a ribbon arranged to wind and unwind between them, clips nearthe ends of the ribbon, slotted levers adapted to be moved by saidclips, a shifting frame movable by said levers, means for restoring saidshiftingv frame to a neutral position, bearings carried by said shiftingframe, a'shaft mounted in said bearings for both rotary and axialrelative motion, a second frame pivoted intermediate the two spools,bearin s for said shaft on said second frame, whereby the shiftingframe, second frame, and shaft are interconnected for oscillatory motionabout the pivot of the second frame, means to steady said shaft in oneor the other of its shifted positions, over-running clutch devicesconnected to drive said spools in opposite directions alternatively,gear wheels adapted to rotate the clutch devices, two driving gearsmounted on said shaft and adapted to drive the gear wheels alternativelyin opposite directions, a ratchet wheel mounted on said shaftintermediate the two driving gears, a ratchet drive mechanism for saidratchet, a air of spaced engaging points on said shifting frame, a pairof differently spaced engaging elements having an oscillatory motion,whereby one or the other of said points on said shifting frame may beengaged when the frame is shifted, and the shaft swung about the pivotto engage one driving gear and disengage the other.

In testimony whereof, I have hereunto signed my name this sixth day ofMay, 1927.

JOHN H. BARR.

